Hallucinations: What Are They, and What Causes Them?

Hallucinations often play a role in television and books about psychiatric hospitals, and may even be used for the purpose of comic relief in discussions of mental illness. But for people experiencing hallucinations, they're very real and often not particularly funny. Although a hallucination can be a symptom of a mental health issue, hallucinations are relatively common, with about 15% of people reporting that they've hallucinated at least once.

What Is a Hallucination?

A hallucination occurs when you see, smell, hear, or feel something that's not actually there. The sensation can be very brief or last for hours. Some people realize they're hallucinating, while others believe that the stimulus is real. This false belief can contribute to a number of issues, and people who have frequent, realistic-seeming hallucinations may live in terror.

While frequent, overwhelming hallucinations are obviously problematic, fleeting hallucinations are relatively common and may not even be perceived as hallucinations. For example, grief hallucinations—catching a glimpse of a deceased person or thinking you hear his or her voice—are so common that some mental health professionals believe they're a normal part of the grieving process. As many as 82% of grieving people have a grief hallucination within a month of a loved one's death.

In some cultures, hallucinations are an important part of religious experience, and people may even take drugs to induce these hallucinations. Many people experience hallucinations when they wake up, and seeing a face or other frightening image in front of your face as you move from sleep to wakefulness is an extremely common—albeit frightening—experience. Lucid dreaming, which occurs when you are aware that you are dreaming and can control the direction of your dreams, is sometimes conceived of as a kind of hallucination.

Why Do They Happen?

People experiencing psychotic states due to bipolar or schizophrenia are especially prone to hallucinations. Some drugs, particularly LSD and other hallucinogens, can induce hallucinations, and people undergoing drug or alcohol withdrawal sometimes hallucinate.

Medical issues such as epilepsy, a very high fever, or a brain tumor may also cause hallucinations, so people who suddenly start experiencing hallucinations should consult a doctor. Fatigue, overwhelming stress, and dementia can also cause people to perceive things that aren't really there.

Because the causes of hallucinations are so varied, doctors typically determine treatment by ruling out potential causes. Antipsychotic drugs can help people experiencing psychotic states, while people experiencing withdrawal may need to be hospitalized to treat the symptoms of withdrawal; in other cases, withdrawal-based hallucinations go away on their own after a few days. When hallucinations are caused by an infection, doctors typically administer intravenous antibiotics and may use other treatments to prevent or mitigate brain damage.

Different Perspectives

Hallucinations are often perceived as one of the most serious consequences of mental illness, and the medical model of mental health care emphasizes the psychological consequences of hallucinations. However, hallucinations have not always been treated this way, and some cultures view hallucinations as a sign of strength or even a sign from a higher power.

Because hallucinations are relatively common, there may be brain mechanisms causing these sensations that science does not yet understand. While one hallucination can be frightening, it does not necessarily indicate a medical problem. Nevertheless, if you experience a hallucination, talk it over with your doctor or mental health care provider.

References:

A.D.A.M. Editor Board. (2012, March 07). Hallucinations. PubMed Health. Retrieved from http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0003742/